Re: [PATCH RFCv2 2/4] i386/pc: relocate 4g start to 1T where applicable

[Joao Martins]

On 2/14/22 15:31, Igor Mammedov wrote:
> On Mon, 14 Feb 2022 15:05:00 +0000
> Joao Martins <joao.m.martins@oracle.com> wrote:
>> On 2/14/22 14:53, Igor Mammedov wrote:
>>> On Mon,  7 Feb 2022 20:24:20 +0000
>>> Joao Martins <joao.m.martins@oracle.com> wrote:
>>>> +{
>>>> +    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
>>>> +    X86MachineState *x86ms = X86_MACHINE(pcms);
>>>> +    ram_addr_t device_mem_size = 0;
>>>> +    uint32_t eax, vendor[3];
>>>> +
>>>> +    host_cpuid(0x0, 0, &eax, &vendor[0], &vendor[2], &vendor[1]);
>>>> +    if (!IS_AMD_VENDOR(vendor)) {
>>>> +        return;
>>>> +    }
>>>> +
>>>> +    if (pcmc->has_reserved_memory &&
>>>> +       (machine->ram_size < machine->maxram_size)) {
>>>> +        device_mem_size = machine->maxram_size - machine->ram_size;
>>>> +    }
>>>> +
>>>> +    if ((x86ms->above_4g_mem_start + x86ms->above_4g_mem_size +
>>>> +         device_mem_size) < AMD_HT_START) {  
>>>   
>> And I was at two minds on this one, whether to advertise *always*
>> the 1T hole, regardless of relocation. Or account the size
>> we advertise for the pci64 hole and make that part of the equation
>> above. Although that has the flaw that the firmware at admin request
>> may pick some ludricous number (limited by maxphysaddr).
> 
> it this point we have only pci64 hole size (machine property),
> so I'd include that in equation to make firmware assign
> pci64 aperture above HT range.
> 
> as for checking maxphysaddr, we can only check 'default' PCI hole
> range at this stage (i.e. 1Gb aligned hole size after all possible RAM)
> and hard error on it.
> 

Igor, in the context of your comment above, I'll be introducing another
preparatory patch that adds up pci_hole64_size to pc_memory_init() such
that all used/max physaddr space checks are consolidated in pc_memory_init().

To that end, the changes involve mainly moves the the pcihost qdev creation
to be before pc_memory_init(). Q35 just needs a 2-line order change. i440fx
needs slightly more of a dance to extract that from i440fx_init() and also
because most i440fx state is private (hence the new helper for size). But
the actual initialization of I440fx/q35 pci host is still after 
pc_memory_init(),
it is just to extra pci_hole64_size from the object + user passed args (-global 
etc).

Raw staging changes below the scissors mark so far.

-->8--

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index b2e43eba1106..902977081350 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -875,7 +875,8 @@ static void x86_update_above_4g_mem_start(PCMachineState 
*pcms)
 void pc_memory_init(PCMachineState *pcms,
                     MemoryRegion *system_memory,
                     MemoryRegion *rom_memory,
-                    MemoryRegion **ram_memory)
+                    MemoryRegion **ram_memory,
+                    uint64_t pci_hole64_size)
 {
     int linux_boot, i;
     MemoryRegion *option_rom_mr;
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index d9b344248dac..5a608e30e28f 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -91,6 +91,8 @@ static void pc_init1(MachineState *machine,
     MemoryRegion *pci_memory;
     MemoryRegion *rom_memory;
     ram_addr_t lowmem;
+    uint64_t hole64_size;
+    DeviceState *i440fx_dev;

     /*
      * Calculate ram split, for memory below and above 4G.  It's a bit
@@ -164,9 +166,13 @@ static void pc_init1(MachineState *machine,
         pci_memory = g_new(MemoryRegion, 1);
         memory_region_init(pci_memory, NULL, "pci", UINT64_MAX);
         rom_memory = pci_memory;
+        i440fx_dev = qdev_new(host_type);
+        hole64_size = i440fx_pci_hole64_size(i440fx_dev);
     } else {
         pci_memory = NULL;
         rom_memory = system_memory;
+        i440fx_dev = NULL;
+        hole64_size = 0;
     }

     pc_guest_info_init(pcms);
@@ -183,7 +189,7 @@ static void pc_init1(MachineState *machine,
     /* allocate ram and load rom/bios */
     if (!xen_enabled()) {
         pc_memory_init(pcms, system_memory,
-                       rom_memory, &ram_memory);
+                       rom_memory, &ram_memory, hole64_size);
     } else {
         pc_system_flash_cleanup_unused(pcms);
         if (machine->kernel_filename != NULL) {
@@ -199,7 +205,7 @@ static void pc_init1(MachineState *machine,

         pci_bus = i440fx_init(host_type,
                               pci_type,
-                              &i440fx_state,
+                              i440fx_dev, &i440fx_state,
                               system_memory, system_io, machine->ram_size,
                               x86ms->below_4g_mem_size,
                               x86ms->above_4g_mem_size,
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 1780f79bc127..b7cf44d4755e 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -203,12 +203,13 @@ static void pc_q35_init(MachineState *machine)
                             pcms->smbios_entry_point_type);
     }

-    /* allocate ram and load rom/bios */
-    pc_memory_init(pcms, get_system_memory(), rom_memory, &ram_memory);
-
     /* create pci host bus */
     q35_host = Q35_HOST_DEVICE(qdev_new(TYPE_Q35_HOST_DEVICE));

+    /* allocate ram and load rom/bios */
+    pc_memory_init(pcms, get_system_memory(), rom_memory, &ram_memory,
+                   q35_host->mch.pci_hole64_size);
+
     object_property_add_child(qdev_get_machine(), "q35", OBJECT(q35_host));
     object_property_set_link(OBJECT(q35_host), MCH_HOST_PROP_RAM_MEM,
                              OBJECT(ram_memory), NULL);
diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
index e08716142b6e..c5cc28250d5c 100644
--- a/hw/pci-host/i440fx.c
+++ b/hw/pci-host/i440fx.c
@@ -237,7 +237,15 @@ static void i440fx_realize(PCIDevice *dev, Error **errp)
     }
 }

+uint64_t i440fx_pci_hole64_size(DeviceState *i440fx_dev)
+{
+        I440FXState *i440fx = I440FX_PCI_HOST_BRIDGE(i440fx_dev);
+
+        return i440fx->pci_hole64_size;
+}
+
 PCIBus *i440fx_init(const char *host_type, const char *pci_type,
+                    DeviceState *dev,
                     PCII440FXState **pi440fx_state,
                     MemoryRegion *address_space_mem,
                     MemoryRegion *address_space_io,
@@ -247,7 +255,6 @@ PCIBus *i440fx_init(const char *host_type, const char 
*pci_type,
                     MemoryRegion *pci_address_space,
                     MemoryRegion *ram_memory)
 {
-    DeviceState *dev;
     PCIBus *b;
     PCIDevice *d;
     PCIHostState *s;
@@ -255,7 +262,6 @@ PCIBus *i440fx_init(const char *host_type, const char 
*pci_type,
     unsigned i;
     I440FXState *i440fx;

-    dev = qdev_new(host_type);
     s = PCI_HOST_BRIDGE(dev);
     b = pci_root_bus_new(dev, NULL, pci_address_space,
                          address_space_io, 0, TYPE_PCI_BUS);
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 9c9f4ac74810..d8b9c4ebd748 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -158,7 +158,8 @@ void xen_load_linux(PCMachineState *pcms);
 void pc_memory_init(PCMachineState *pcms,
                     MemoryRegion *system_memory,
                     MemoryRegion *rom_memory,
-                    MemoryRegion **ram_memory);
+                    MemoryRegion **ram_memory,
+                    uint64_t pci_hole64_size);
 uint64_t pc_pci_hole64_start(void);
 DeviceState *pc_vga_init(ISABus *isa_bus, PCIBus *pci_bus);
 void pc_basic_device_init(struct PCMachineState *pcms,
diff --git a/include/hw/pci-host/i440fx.h b/include/hw/pci-host/i440fx.h
index f068aaba8fda..1299d6a2b0e4 100644
--- a/include/hw/pci-host/i440fx.h
+++ b/include/hw/pci-host/i440fx.h
@@ -36,7 +36,7 @@ struct PCII440FXState {
 #define TYPE_IGD_PASSTHROUGH_I440FX_PCI_DEVICE "igd-passthrough-i440FX"

 PCIBus *i440fx_init(const char *host_type, const char *pci_type,
-                    PCII440FXState **pi440fx_state,
+                    DeviceState *dev, PCII440FXState **pi440fx_state,
                     MemoryRegion *address_space_mem,
                     MemoryRegion *address_space_io,
                     ram_addr_t ram_size,
@@ -45,5 +45,6 @@ PCIBus *i440fx_init(const char *host_type, const char 
*pci_type,
                     MemoryRegion *pci_memory,
                     MemoryRegion *ram_memory);

+uint64_t i440fx_pci_hole64_size(DeviceState *i440fx_dev);

 #endif